[world-vercel] Fail the run on a lost event payload instead of retrying forever by VaguelySerious · Pull Request #3742 · vercel/workflow

VaguelySerious · 2026-08-22T00:30:14Z

Problem

A frame stream commits to 200 with its first byte, so a failure partway through the body has no status code left to carry it. The World's only way to signal one was to error the body, which reaches us as a truncated response. That is also exactly what a dropped socket looks like, so the runtime could not tell "retry me" from "this can never work" and kept redelivering.

When the failure is an event payload that no longer exists in storage, every redelivery re-reads the same absent object. One production run re-read a single missing payload 12,932 times in 26 minutes, and the backend event query behind each attempt is what throttled its table.

Change

The World now ends such a stream with a terminal {_error: 1, code, message} frame instead of erroring the body. This PR consumes it:

payload-missing → CorruptedEventLogError, so the run fails with CORRUPTED_EVENT_LOG. That is accurate: the log references a payload nothing can produce.
Any other code → WorkflowWorldError with no retryable code and no status, so it is terminal too. A code this client has never heard of does not become a redelivery loop, and a future one can be handled explicitly later without needing a client release first.

Transient failures are unchanged: the World still errors the body for those, and the runtime still redelivers, which is the right move.

Compatibility

The decoder already rejected any unrecognized _-prefixed control frame, so a client without this change fails loudly on the new frame rather than mistaking a short log for a complete one. It still retries; only a client that knows the code can stop.

Tests

payload-missing produces a CorruptedEventLogError naming the ref, and is not a WorkflowWorldError (so not redelivered).
An unknown terminal code produces a terminal WorkflowWorldError (no status, non-retryable code).
packages/core: isRetryableWorldError(CorruptedEventLogError) is false, next to the existing CORRUPTED_EVENT_LOG mapping assertion.

Full @workflow/world-vercel suite passes (558 tests).

Notes

Draft until the World-side change ships. WORKFLOW_SERVER_URL_OVERRIDE is back to '', so E2E here runs against the deployed World and does not exercise the new frame end to end. The frame decoding is covered by the mocked-transport tests above.
CORRUPTED_EVENT_LOG docs updated to mention an unreadable stored payload as a cause.

…trying A frame stream that dies mid-body reaches us as a truncated response, which is exactly what a dropped socket looks like. So an event whose stored payload is permanently gone was indistinguishable from a transient blip, and the runtime kept redelivering a replay that could never succeed: one run re-read a single missing payload 12,932 times in 26 minutes, and the backend query behind each attempt throttled its table. The World now sends a terminal `{_error: 1, code}` frame for failures that a retry cannot fix. Handle it: - `payload-missing` raises `CorruptedEventLogError`, so the run fails with `CORRUPTED_EVENT_LOG` rather than looping. The log does reference a payload nothing can produce. - An unknown code raises a `WorkflowWorldError` with no retryable code and no status, which is also terminal. A future code stays safe without needing a client release first. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

changeset-bot · 2026-08-22T00:30:18Z

🦋 Changeset detected

Latest commit: 3292086

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 17 packages

Name	Type
@workflow/world-vercel	Patch
@workflow/cli	Patch
@workflow/core	Patch
@workflow/web	Patch
workflow	Patch
@workflow/world-testing	Patch
@workflow/builders	Patch
@workflow/next	Patch
@workflow/nitro	Patch
@workflow/vitest	Patch
@workflow/web-shared	Patch
@workflow/astro	Patch
@workflow/nest	Patch
@workflow/rollup	Patch
@workflow/sveltekit	Patch
@workflow/vite	Patch
@workflow/nuxt	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

vercel · 2026-08-22T00:30:21Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 25, 2026 9:28pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 25, 2026 9:28pm
example-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-astro-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-express-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-hono-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-python-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workbench-vite-workflow	Ready	Preview, v0	Aug 25, 2026 9:28pm
workflow-docs	Ready	Preview, v0	Aug 25, 2026 9:28pm
workflow-swc-playground	Ready	Preview, v0	Aug 25, 2026 9:28pm
workflow-tarballs	Ready	Preview, v0	Aug 25, 2026 9:28pm
workflow-web	Ready	Preview, v0	Aug 25, 2026 9:28pm

github-actions · 2026-08-22T00:30:32Z

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

promiseAllWorkflow | wrun_41M0XD5CBZ0GPQBYMHJEF871DE | 🔍 observability
sleepingWorkflow | wrun_41M0XD61H20GYPG0P49B4EJ236 | 🔍 observability
parallelSleepWorkflow | wrun_41M0XD623R0GVR5XAA06CVX52A | 🔍 observability
nullByteWorkflow | wrun_41M0XD68SQ0GGA82NPYJNGY8J8 | 🔍 observability
cancelRun - cancelling a running workflow | wrun_41M0XDASFR0GMEF6ZQT8YEFZVR | 🔍 observability
cancelRun via CLI - cancelling a running workflow | wrun_41M0XDATNX0GKY2Z4N1CZFRTSX | 🔍 observability
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0XDB20A0GW338SHE0W52EW1 | 🔍 observability
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0XDBMDM0GXMF92MV7X82MNH | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0XD8QG8RPWAWSQ5XWQZSEMP
promiseAllWorkflow | wrun_41M0XD5CBZ0GPQBYMHJEF871DE
sleepingWorkflow | wrun_41M0XD61H20GYPG0P49B4EJ236
parallelSleepWorkflow | wrun_41M0XD623R0GVR5XAA06CVX52A
nullByteWorkflow | wrun_41M0XD68SQ0GGA82NPYJNGY8J8
cancelRun - cancelling a running workflow | wrun_41M0XDASFR0GMEF6ZQT8YEFZVR
cancelRun via CLI - cancelling a running workflow | wrun_41M0XDATNX0GKY2Z4N1CZFRTSX
sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0XDB20A0GW338SHE0W52EW1
resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0XDBMDM0GXMF92MV7X82MNH

⚠️ Flaky E2E Tests (passed on retry)

These tests failed at least once and passed on a retry. A recurring entry here is a real race worth investigating.

addTenWorkflow (nest)
cancelRun via CLI - cancelling a running workflow (astro)
cancelRun via CLI - cancelling a running workflow (nextjs-turbopack)
deploymentId: 'latest' is a no-op in non-Vercel worlds (express)
promiseAllWorkflow (hono)
sleepWinsRaceWorkflow (vite)

🛠 Infra Events (absorbed by the harness)

Platform anomalies the e2e harness detected and worked around (e.g. a run the queue never picked up, replaced by a fresh run). Clustered timestamps indicate a backend blip; a steady drip indicates a platform issue worth escalating.

33 infra events

cold-start-warmup · suite warmup (tanstack-start) · at 21:27:19Z · abandoned wrun_01M0XD38K7B2VSWXEV2KDCHDR0
cold-start-warmup · suite warmup (python) · at 21:27:55Z · abandoned wrun_41M0XD1H3M0GSC20T4552XJWMK · (+7 more)
run-pickup-stall · promiseAllWorkflow (python) · at 21:28:11Z · abandoned wrun_41M0XD55YJ0GWN4FC3MTSQWX4X
run-pickup-stall · nullByteWorkflow (python) · at 21:28:11Z · abandoned wrun_41M0XD55YX0GNJ1SGM5MFPYPCQ
run-pickup-stall · sleepingWorkflow (python) · at 21:28:11Z · abandoned wrun_41M0XD55YS0GXP9M7YWSB5Z0HW
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 21:28:11Z · abandoned wrun_41M0XD56C70GXYTEYRC44CDTJV
run-pickup-stall · parallelSleepWorkflow (python) · at 21:28:11Z · abandoned wrun_41M0XD55YS0GXP9M7YWSB5Z0HX
cold-start-warmup · suite warmup (python) · at 21:28:36Z · abandoned wrun_01M0XD2S2GVKDXANB0JPF27S85 · (+7 more)
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 21:28:44Z · abandoned wrun_41M0XD66H00GS0SRG2XC8SVP9R
run-pickup-stall · sleepingWorkflow (python) · at 21:28:51Z · abandoned wrun_01M0XD6E7MSJ4HPCMH5T104X1K
run-pickup-stall · parallelSleepWorkflow (python) · at 21:28:51Z · abandoned wrun_01M0XD6E7NSDA6XHVYQCDJVYH0
run-pickup-stall · nullByteWorkflow (python) · at 21:28:51Z · abandoned wrun_01M0XD6E7QHJRXAF3CRHG41RMS
run-pickup-stall · promiseAllWorkflow (python) · at 21:28:51Z · abandoned wrun_01M0XD6E7G493ER132X9EM7Q58
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 21:28:51Z · abandoned wrun_01M0XD6E7FPZEK9TAT7RWZM0FQ
run-pickup-stall · sleepingWorkflow (python) · at 21:29:12Z · abandoned wrun_41M0XD71GF0GG9FYVP3467KYRX
run-pickup-stall · promiseAllWorkflow (python) · at 21:29:12Z · abandoned wrun_41M0XD71EW0GSKMKT1Z101J157
run-pickup-stall · nullByteWorkflow (python) · at 21:29:12Z · abandoned wrun_41M0XD71HK0GGXYDJDYJVDJKCV
run-pickup-stall · parallelSleepWorkflow (python) · at 21:29:12Z · abandoned wrun_41M0XD71GY0GTN381PE11PEY96
run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 21:29:51Z · abandoned wrun_01M0XD88V19SA17Q9T4KMRQ061
run-pickup-stall · sleepingWorkflow (python) · at 21:29:51Z · abandoned wrun_01M0XD88V510VBKY2DSJW1JJ33
run-pickup-stall · promiseAllWorkflow (python) · at 21:29:51Z · abandoned wrun_01M0XD88V29HAY32382EV6TBY4
run-pickup-stall · nullByteWorkflow (python) · at 21:29:51Z · abandoned wrun_01M0XD88VEFRS1H54949D0525D
run-pickup-stall · parallelSleepWorkflow (python) · at 21:29:51Z · abandoned wrun_01M0XD88V72552BFW9D2GK6H4V
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 21:30:02Z · abandoned wrun_41M0XD765A0GN4G41HM4RXVFEP
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 21:30:51Z · abandoned wrun_01M0XDA3EMKG7KC4T7ZHM91DX2
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 21:30:51Z · abandoned wrun_01M0XDA3ESEH89QGFXVWDGGH00
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 21:30:51Z · abandoned wrun_01M0XDA3EX8NN3J8P0QKS5GPHC
run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 21:31:21Z · abandoned wrun_01M0XDB0T1FKYYETQ2AYX6RAWY
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 21:31:21Z · abandoned wrun_01M0XDB0T2PG62XJNY5FDWJX6T
run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 21:31:43Z · abandoned wrun_41M0XD9Y1W0GW66FRRR049QTY5
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 21:31:44Z · abandoned wrun_41M0XD9SBE0GV97Q3AXX5RVEPX
run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 21:31:51Z · abandoned wrun_01M0XDBY1ZYJCVCYXPGHXBJH61
run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 21:34:58Z · abandoned wrun_01M0XDHN2W2B6A2WRX6AQKD8V5

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	134	26
✅ astro-stable-quickjs	134	26
✅ express-stable-node	134	26
✅ express-stable-quickjs	134	26
✅ fastify-stable-node	134	26
✅ fastify-stable-quickjs	134	26
✅ hono-stable-node	134	26
✅ hono-stable-quickjs	134	26
✅ nest-stable-node	134	26
✅ nest-stable-quickjs	134	26
✅ nextjs-turbopack-canary-node	141	19
✅ nextjs-turbopack-canary-quickjs	141	19
✅ nextjs-turbopack-stable-node	160	0
✅ nextjs-turbopack-stable-quickjs	160	0
✅ nextjs-webpack-canary-node	141	19
✅ nextjs-webpack-canary-quickjs	141	19
✅ nextjs-webpack-stable-node	160	0
✅ nextjs-webpack-stable-quickjs	160	0
✅ nitro-stable-node	134	26
✅ nitro-stable-quickjs	134	26
✅ nuxt-stable-node	134	26
✅ nuxt-stable-quickjs	134	26
✅ sveltekit-stable-node	153	7
✅ sveltekit-stable-quickjs	153	7
✅ tanstack-start-node	134	26
✅ tanstack-start-quickjs	134	26
✅ vite-stable-node	134	26
✅ vite-stable-quickjs	134	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Skipped
✅ example	132	28
✅ express	132	28
✅ hono	132	28
✅ nextjs-turbopack	157	3
✅ nitro	132	28
✅ vite	132	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Skipped
✅ example	132	28
✅ express	132	28
✅ nextjs-turbopack	157	3
✅ vite	132	28

📋 View full workflow run

github-actions · 2026-08-22T00:30:34Z

📊 Workflow Benchmarks

commit 3292086 · Tue, 25 Aug 2026 21:42:07 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	247 (+15%)	1279 🔴 (+30%) 🔻	1316 🔴 (+28%) 🔻	1340 🔴 (-7.2%)	30
TTFS	stream	1183 (+554%) 🔻	1262 🔴 (+33%) 🔻	1271 🔴 (+32%) 🔻	1281 🔴 (+27%) 🔻	30
TTFS	hook + stream	441 (-15%)	1588 🔴 (+18%) 🔻	1633 🔴 (+8.9%)	6071 🔴 (+19%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	509 (-9.1%)	770 (-23%) 💚	808 (-43%) 💚	1338 (-18%) 💚	10
Fan-out TTLS	Promise.all(100 steps)	1900 (-2.0%)	4056 (+47%) 🔻	4527 (+35%) 🔻	7752 (+18%) 🔻	10
STSO	1020 steps (inline)	110 (+2.8%)	130 (±0%)	147 (-3.3%)	180 (-12%)	1019
WO	1020 steps	132798 (±0%)	132798 (±0%)	132798 (±0%)	132798 (±0%)	1
CRTT	first chunk (pooled)	87 (+3.6%)	132 (-0.8%)	151 (-2.6%)	209 (-13%)	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	130 (+18%)	147 (-9%)	470 (+14%)	688 (+8%)	257 (+98%)	10
size sweep (100/s, 160B-12KB)	106 (-4%)	124 (-9%)	177 (-50%)	332 (-58%)	132 (+26%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	138 (-6%)	113 (-18%)	140 (-46%)	374 (-58%)	244 (-27%)	3
replay eve-gpt-5.6-sol-2000t (1x)	142 (-22%)	116 (-6%)	144 (-11%)	313 (-6%)	214 (-33%)	2
replay eve-gpt-5.6-sol-2000t (2x)	115 (-9%)	147 (-1%)	220 (+14%)	375 (-1%)	187 (-28%)	3

📈 STSO distribution vs main (inline / queue-hop histograms)

1020 steps (inline)

Cumulative STSO time: main 132084ms → this run 131580ms (Δ -504ms, 0%)

100-150 ms  ███████████████████████┃  main 905  this 937   +32
150-200 ms  █┃█                       main 103  this  77   -26
200-250 ms  ┃                         main   5  this   3    -2
250-300 ms  ┃                         main   2  this   1    -1
300-350 ms  ┃                         main   1  this   0    -1
350-400 ms  ┃                         main   1  this   1    +0
400-450 ms  ┃                         main   2  this   0    -2

📈 CRTT drill-down vs main (RTT distributions & profiles)

variant  RTT 1ms→5s+             avg        p50         p90         p99     n
control  ······██▂▁···   129.6 (+3%)  101 (+2%)  470 (+14%)   688 (+8%)  3000
sweep    ······██▁····   106.4 (-9%)   99 (+1%)  177 (-50%)  332 (-58%)  3000
gw 1x    ·····▁█▅▁····  100.4 (-16%)   93 (-3%)  140 (-46%)  374 (-58%)  5295
eve 1x   ·····▁█▅▁····    98.6 (-8%)   88 (-8%)  144 (-11%)   313 (-6%)  5186
eve 2x   ·····▁▆█▂····   124.4 (±0%)  113 (-3%)  220 (+14%)   375 (-1%)  7779

RTT over stream progress (avg per tenth of stream, bars scaled min→max):

control  ▅▇▆▂▇▆█▇▂▁  101–151ms
sweep    ▅▃▁▃▅▄▃▆█▂  95–121ms
gw 1x    ▇▄▂▄▁▂█▃▄▃  90–116ms
eve 1x   ▅▅▅▁▁▁▄█▄▁  90–114ms
eve 2x   ▃▂▃▂▁▂▆█▃▁  103–171ms

RTT by chunk size (avg per log size bin, ~160B → ~12KB serialized, bars scaled min→max):

sweep  ▇▅█▆▂▁▄  105–108ms

Delivery jitter over stream progress (avg positive CDV per tenth of stream, bars scaled min→max):

control  ▁▆▃▂█▂█▃▁▂  29–45ms
sweep    ▁▄▂▂▆▅▄█▆▂  33–50ms
gw 1x    █▅▁▂▂▄▇▄▂▃  26–32ms
eve 1x   ▇█▁▁▃▃▇▆▅▆  19–22ms
eve 2x   █▂▁▃▁▃▆▁▁▃  19–26ms

📜 Previous results (2)

`f68d1a4`

Tue, 25 Aug 2026 21:22:40 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1127 (+424%) 🔻	1285 🔴 (+30%) 🔻	1313 🔴 (+28%) 🔻	1367 🔴 (-5.3%)	30
TTFS	stream	235 (+30%) 🔻	1267 🔴 (+33%) 🔻	1285 🔴 (+33%) 🔻	1327 🔴 (+31%) 🔻	30
TTFS	hook + stream	484 (-6.4%)	1550 🔴 (+15%)	1583 🔴 (+5.6%)	1587 🔴 (-69%) 💚	30
Fan-out TTFS	Promise.all(100 steps)	613 (+9.5%)	825 (-17%) 💚	832 (-41%) 💚	2148 (+32%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	4249 (+119%) 🔻	6397 (+131%) 🔻	6650 (+99%) 🔻	12424 (+89%) 🔻	10
STSO	1020 steps (inline)	75 (-30%) 💚	106 (-18%) 💚	121 (-20%) 💚	176 (-14%)	1019
WO	1020 steps	106955 (-19%) 💚	106955 (-19%) 💚	106955 (-19%) 💚	106955 (-19%) 💚	1
CRTT	first chunk (pooled)	89 (+6.0%)	182 (+37%) 🔻	215 (+39%) 🔻	387 (+62%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	113 (+2%)	144 (-11%)	364 (-12%)	755 (+19%)	162 (+25%)	10
size sweep (100/s, 160B-12KB)	125 (+13%)	125 (-9%)	170 (-52%)	498 (-37%)	135 (+29%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	122 (-17%)	113 (-18%)	140 (-46%)	364 (-59%)	185 (-44%)	3
replay eve-gpt-5.6-sol-2000t (1x)	274 (+50%)	120 (-2%)	153 (-6%)	335 (+1%)	340 (+7%)	2
replay eve-gpt-5.6-sol-2000t (2x)	186 (+46%)	149 (±0%)	232 (+20%)	428 (+14%)	275 (+6%)	3

`3ea2135`

Sat, 22 Aug 2026 00:49:31 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	211 (-79%) 💚	1297 🔴 (+13%)	1323 🔴 (+12%)	1346 🔴 (+2.9%)	30
TTFS	stream	231 (-78%) 💚	1324 🔴 (+17%) 🔻	1368 🔴 (+17%) 🔻	1404 🔴 (+16%) 🔻	30
TTFS	hook + stream	455 (-62%) 💚	1541 🔴 (+8.5%)	1629 🔴 (+8.8%)	1708 🔴 (-11%)	30
Fan-out TTFS	Promise.all(100 steps)	565 (-24%) 💚	997 (-48%) 💚	1122 (-42%) 💚	2219 (+9.3%)	10
Fan-out TTLS	Promise.all(100 steps)	9742 (+94%) 🔻	16071 (+115%) 🔻	16819 (+113%) 🔻	17975 (+109%) 🔻	10
STSO	1020 steps (inline)	95 (-8.7%)	138 (-2.8%)	161 (±0%)	360 (+85%) 🔻	1019
WO	1020 steps	140874 (-1.2%)	140874 (-1.2%)	140874 (-1.2%)	140874 (-1.2%)	1
CRTT	first chunk (pooled)	95 (-22%) 💚	143 (-19%) 💚	234 (+6.4%)	300 (-46%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-14%)	262 (-44%)	365 (-44%)	964 (-82%)	239 (+54%)	10
size sweep (100/s, 160B-12KB)	123 (-25%)	142 (-29%)	208 (-32%)	745 (+64%)	155 (-17%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	119 (-34%)	131 (-50%)	178 (-69%)	304 (-79%)	218 (-73%)	3
replay eve-gpt-5.6-sol-2000t (1x)	128 (-15%)	144 (-23%)	181 (-48%)	366 (-73%)	368 (-54%)	2
replay eve-gpt-5.6-sol-2000t (2x)	131 (-26%)	316 (+17%)	2968 (+683%)	4521 (+534%)	3388 (+816%)	3

ℹ️ Metric definitions & methodology

_{Streams: first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach.}

_{The collapsed STSO distribution section above buckets every step gap, split inline (same warm process — pure framework overhead) vs queue-hop (fresh process — dispatch, reinit, replay). █ = main, ┃ = this run, ░ = fill.}

_{The collapsed CRTT drill-down: per-variant RTT histograms (fixed log bins, · = empty) and mean RTT/positive-CDV profile lines over stream progress and chunk size. Histograms, avgs, and profiles merge exactly across runs; p50–p99 are percentile-of-percentiles. Per-index rows live in the artifacts.}

_{Best/P75/P90/P99 deltas compare against the most recent benchmark run on main at the time of this run. 🔻 flags a delta worse than +15%, 💚 one better than −15%.}

_{Metrics — TTFS: time to first step body (in-deployment start() → first step body) · Fan-out TTFS: fan-out time to first step (in-deployment start() → first of the parallel step bodies to complete) · Fan-out TTLS: fan-out time to last step (in-deployment start() → last of the parallel step bodies to complete, i.e. when the Promise.all resolves) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · CRTT: chunk round-trip time (per-chunk write → read latency, one clock domain: deployment → stream backend → same deployment) · CDV: chunk delay variation / delivery jitter (inter-arrival gap minus inter-write gap per seq-adjacent pair; skew-free; the row is each run's MAX positive value, so one stall moves it)}

_{Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · Promise.all(100 steps): 100 trivial no-op steps started together in a single Promise.all; Fan-out TTFS is the first of them to complete and Fan-out TTLS the last, both from the in-deployment clientStart, so their gap is the spread the runtime adds across the fan-out · paced control (100/s, 60B): the control: 300 tiny (~60B) deltas metronome-paced at 100/s — zero workload structure, so it reads the transport floor and flush cadence, and disambiguates transport-wide vs workload-specific when a replay row moves · size sweep (100/s, 160B-12KB): same pacing as the control with deltas padded in rotation across seven log-spaced sizes (~160B–12KB) — rotation decouples size from stream position, so it isolates whether chunk size causes latency · replay gateway-gpt-5.4-nano-2000t (1x): raw provider SSE cadence captured at the AI gateway boundary (gpt-5.4-nano, the most popular gateway model; per-token deltas p50 208B = the modal production chunk size), replayed exactly as measured — the typical customer's workload; its CDV is the typical customer's real delivery jitter · replay eve-gpt-5.6-sol-2000t (1x): a captured eve turn (gpt-5.6-sol, the most-used demanding eve model; ~2000 output tokens = production p50 turn length) replayed exactly as measured — eve's envelope protocol re-ships the cumulative message so sizes ramp 142B→13KB; the demanding outlier tenant's reality · replay eve-gpt-5.6-sol-2000t (2x): the same eve capture at 2x — the headroom/stress row; real fast-tier models emit the same chunk sizes at proportionally higher rate, so time compression is a faithful speed model · first chunk (pooled): every run's seq-0 RTT pooled across all stream scenarios — the first chunk precedes any workload differentiation, so pooling samples one shared stream-open path with exact percentiles}

_{Replay cadences (semantic sha256) — eve-gpt-5.6-sol-2000t eaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t 6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600}

_{All timestamps are deployment-side; runs are triggered in-deployment, so the CI runner and api.vercel.com sit outside every measured window. TTFS = start() → first step body (includes dispatch + any cold start); Fan-out TTFS/TTLS = first/last step completion of one Promise.all from the same anchor (the gap is the runtime’s fan-out spread); STSO/WO between step bodies; CRTT inside the workflow (excludes the api.vercel.com read path).}

_{Cold starts stay in the numbers (real bursty-workload latency, inflates P75+); Best is the warm floor.}

github-actions · 2026-08-22T00:33:51Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

scenario	outcome	events	virt	replay
✅ `smoke-no-steps`	completed	3	0ms	ok
✅ `smoke-one-step`	completed	6	0ms	ok
✅ `hook-at-step-started`	completed	12	0ms	ok
✅ `hook-at-step-completed`	completed	12	0ms	ok
✅ `hook-at-hook-created`	completed	12	0ms	ok
✅ `deadline-hook-wins`	completed	7	1.0h	ok
✅ `deadline-expires`	completed	7	1.0h	ok
✅ `long-sleep`	completed	11	30.0d	ok
✅ `hook-never-arrives`	stalled	3	0ms	skipped
✅ `step-retries-twice`	completed	10	2.0s	ok
✅ `parallel-steps`	completed	9	0ms	ok
✅ `hook-on-execution-state`	completed	12	0ms	ok
✅ `peek-hook-before-branch`	completed	12	0ms	ok
✅ `peek-hook-after-branch`	completed	12	0ms	ok
✅ `peek-hook-at-registration`	completed	12	0ms	ok
✅ `race-hook-before-probe`	completed	12	0ms	ok
✅ `race-hook-after-probe`	completed	12	0ms	ok
✅ `race-duplicate-delivery`	completed	13	0ms	ok
✅ `attr-hook-before-step`	completed	11	0ms	ok
✅ `attr-hook-after-step`	completed	11	0ms	ok
✅ `attr-from-step-body`	completed	13	0ms	ok
✅ `fork-hook-after-timeout`	completed	14	1.0m	ok
✅ `fork-hook-before-timeout`	completed	14	1.0m	ok
✅ `count-hook-after-timeout`	completed	17	1.0m	ok
✅ `count-hook-before-timeout`	completed	20	1.0m	ok
✅ `stale-read-step-count-fork`	completed	20	1.0m	ok
✅ `stale-read-equal-step-counts`	completed	14	1.0m	ok
✅ `step-vs-step-fork`	completed	12	0ms	ok
✅ `step-vs-step-fork-fenced`	completed	12	0ms	ok
✅ `fence-catches-benign-direction`	completed	12	5ms	ok
✅ `in-flight-before-decision`	completed	17	1.0m	ok
❌ `in-flight-before-decision-counted`	completed	17	1.0m	ok
✅ `in-flight-after-decision`	completed	19	2.0m	ok
✅ `stale-read-step-count-fork-fenced`	completed	20	1.0m	ok
✅ `fork-hook-wins`	completed	13	1.0m	ok
✅ `fork-timeout-wins`	completed	13	1.0m	ok
✅ `unclaimed-payload-under-fork`	completed	17	1.0m	ok
✅ `claimed-payload-under-fork`	completed	17	1.0m	ok
✅ `writers-independent-step-bodies`	completed	12	0ms	ok
✅ `writers-scripted-tempo`	completed	12	0ms	ok
✅ `cancel-mid-step`	cancelled	7	0ms	skipped

Full trace: world-sim.txt

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

github-actions · 2026-08-25T21:10:15Z

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.5 KiB (±0)	1.76 MiB (+773 B)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.0 KiB (+188 B)

About these numbers

Sizes are gzip; parentheses show the change against main.
Flow route and Step reg. gate this job, on raw bytes rather than the gzip shown, at max(2%, 50.0 KiB). Framework output is informational.

3292086 · run

karthikscale3 · 2026-08-25T22:42:30Z

+  }
+  return new WorkflowWorldError(
+    `v4 ${opName}: stream ended with terminal error "${code}": ${detail}`,
+    { code: 'INVALID_RESPONSE' }


AI Review: Unknown terminal codes are converted to WorkflowWorldError with code: "INVALID_RESPONSE", but isWorldContractError recognizes only PARSE_ERROR, SCHEMA_VALIDATION, and WORLD_CONTRACT_ERROR. This falls through to USER_ERROR, even though an unknown server control code is a backend protocol condition. Please use a world-contract code (or extend the classifier) and add a classification assertion.

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Revert the world-vercel URL override to empty

f68d1a4

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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Merge main into peter/v4-terminal-payload-missing

3292086

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VaguelySerious marked this pull request as ready for review August 25, 2026 21:51

VaguelySerious requested review from a team, fantix and msullivan as code owners August 25, 2026 21:51

karthikscale3 reviewed Aug 25, 2026

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[world-vercel] Fail the run on a lost event payload instead of retrying forever - #3742

[world-vercel] Fail the run on a lost event payload instead of retrying forever#3742
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🧪 E2E Test Results

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

🌐 Cross-language Conformance (9 failed)

⚠️ Flaky E2E Tests (passed on retry)

🛠 Infra Events (absorbed by the harness)

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📊 Workflow Benchmarks

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